DESCRIPTION The long-term objectives of this project are to determine how the presence of the fertilized embryo modifies the uterine environment for the establishment and maintenance of successful pregnancy. The first specific aim extends the proposed studies in the parent grant by comparing the influence of an embryonic signal (simulated-pregnant baboon model) to that of the embryo itself on the uterine environment. The second specific aim utilizes the baboon to study the enigmatic clinical disease, endometriosis, by comparing the effects of the disease on the oviduct and the uterus at critical times in the reproductive process (post-ovulatory days 8 - 12, which correspond to apposition, attachment, and penetration of the trophoblast to the endometrium).